Sydneysiders are being warned to brace themselves for wild weather with heavy rainfall expected to cause flash flooding in the city and elsewhere across NSW. The Bureau of Meteorology on Monday issued a flood watch and severe weather warning with a low-pressure system likely to dump heavy rain on coastal areas from Wednesday morning. Flash flooding, damaging winds and hazardous surf conditions are anticipated. Bureau forecaster Anita Pyne says the heaviest falls will likely be over the Sydney and Illawarra districts but the northern part of the South Coast, Central Coast and Blue Mountains could also be hard hit. The majority of the storm will be over in a six to 12-hour period from Wednesday morning. Sydney and the Illawarra are predicted to receive up to 100 millimetres of rain with localised totals that could exceed 200mm, Ms Pyne said in a statement. Australian Associated Press

Bureau forecaster Anita Pyne says the heaviest falls will likely be over the Sydney and Illawarra districts but the northern part of the South Coast, Central Coast and Blue Mountains could also be hard hit.

The majority of the storm will be over in a six to 12-hour period from Wednesday morning.

Sydney and the Illawarra are predicted to receive up to 100 millimetres of rain with localised totals that could exceed 200mm, Ms Pyne said in a statement.